Isn’t this feature supposed to add an image over the entire background of a spreadsheet or does it do something else? If I go to Format > Page > Background > Bitmap and even if I select one of the default images that’s there and click OK on a brand new, blank, sheet I just opened it doesn’t apply it to the sheet. I can’t apply a background color to an entire sheet either. Nothing happens at all.
It doesn’t show in File -> Print Preview
at all (you tagged Calc, and hence it is shown only on printing the document)? For me this works using:
Version: 7.2.0.4 / LibreOffice Community
Build ID: 9a9c6381e3f7a62afc1329bd359cc48accb6435b
CPU threads: 8; OS: Linux 5.3; UI render: default; VCL: kf5 (cairo+xcb)
Locale: pt-BR (en_US.UTF-8); UI: en-US
Calc: threaded
Ref.
Formatting Spreadsheets stating:
An image that you have loaded with Format - Page - Background is only visible in print or in the print preview. To display a background image on screen as well, insert the graphic image by choosing Insert - Image - From File and arrange the image behind the cells by choosing Format - Arrange - To Background. Use the Navigator to select the background image.
I’m not trying to print it I was playing around, surfing the menus and testing things out. I went in to options and did the check now for an update. It said
LibreOffice 7.1 is up to date.
Version: 7.1.5.2 (x64) / LibreOffice Community
Build ID: 85f04e9f809797b8199d13c421bd8a2b025d52b5
CPU threads: 4; OS: Windows 10.0 Build 19043; UI render: Skia/Raster; VCL: win
Locale: en-US (en_US); UI: en-US
Calc: threaded
ok. Thank you!
Where do I find those references?
… then you can’t see the effect of your setting in Calc. See my first comment.
The link to LibreOffice Online Help is given in my comment.
Thanks. Why was it made like that to only show in print preview?

Why was it made like that to only show in print preview?
Let me ask a (rhetorical) counter question: What should be the benefit of having an image background on a calculation tool (I can’t imagine any, however there is a way to have an image background visible - also given in Ref.)?

What should be the benefit of having an image background
For the same reasons anyone should want to see what they’re creating, especially for print, in any tool or computer program. So you can see it. Cosmetics. I see why Libre office is failing to influence people and businesses to migrate to it from the expensive Microsoft suites. Would you write with invisible ink? Same thing. It’s dumb to have it that way.
Draw or Writer are better suited to cosmetics.